Well conduit lining method and system

ABSTRACT

A method of performing an operation in a well having a conduit includes deploying a tube liner having a lay-flat state into a tubular structure positioned in the well. Fluid is injected into the tube liner to radially expand the tube liner to conform to a tubular wall surface of the tubular structure and thereby provide a protected portion of the conduit within the tubular structure.

FIELD

The disclosure relates generally to a method and a system for protecting well tubulars from corrosive fluids downhole.

BACKGROUND

Tubulars are installed in wells to provide a conduit from the well to the surface and to support the wall of the well. However, once the well starts producing water, corrosion of these tubulars becomes a concern. In order to prevent corrosion of well tubulars, several methods are used, such as injecting chemical inhibitors into the well, lining the tubulars with protective coatings, and lining the tubulars with high grade alloys such as chromium or nickel based alloys. However, these methods are either inefficient or relatively expensive in terms of cost and logistics.

SUMMARY

A method of performing an operation in a well having a conduit includes deploying a tube liner having a lay-flat state into a tubular structure that is positioned in the well. The method includes injecting fluid into the tube liner to radially expand the tube liner to conform to a tubular wall surface of the tubular structure and thereby provide a protected portion of the conduit within the tubular structure. The tube liner may have an unstretched full diameter in a round state that is larger than an inner diameter of the tubular structure. Injecting fluid into the tube liner may include transforming the tube liner from the lay-flat state to a round state. Deploying the tube liner may include providing a continuous lay-flat tubing on a spool, spooling out the continuous lay-flat tubing into the tubular structure, terminating the spooling out when a select length of the continuous lay-flat tubing has been deployed into the tubular structure, and securing the select length of the continuous lay-flat tubing deployed into the tubular structure at a surface above the well. Spooling out the continuous lay-flat tubing may include attaching a dissolvable weight to an end of the continuous lay-flat tubing that is fed into the tubular structure. Alternatively, spooling out the continuous lay-flat tubing may include coupling a tractor to an end of the continuous lay-flat tubing that is fed into the tubular structure and operating the tractor to move along the tubular structure. The tube liner may be a lay-flat tubing made of a film material. The film material may comprise a thermoplastic polymer. The thickness of the film material may range from 0.25 mil to 10 mil. The film material may have a temperature rating of at least 70° C. Alternatively, the tube liner may be a lay-flat tubing made of a flexible fiber-reinforced thermoplastic material. The fiber-reinforced thermoplastic material may have a temperature rating of at least 70° C. The well may penetrate an injection zone, and the method may include conveying fluid into the injection zone by pumping fluid through the protected portion of the conduit.

A system for performing an operation in a well includes a tubular structure disposed in the well to provide at least a portion of a conduit in the well. The tubular structure has a tubular wall surface. The system includes a spool carrying a continuous lay-flat tubing. The spool is disposed at a surface above the well. The spool is operable to deploy at least a portion of the continuous lay-flat tubing into the tubular structure in the well. The system includes a pump positioned to inject fluid into the at least a portion of the continuous lay-flat tubing disposed inside the tubular structure. The continuous lay-flat tubing may be made of a film material comprising a thermoplastic polymer. The film material may have a thickness in a range from 0.25 mil to 10 mil. The film material may have a temperature rating of at least 70° C. Alternatively, the continuous lay-flat tubing may be made of a flexible fiber-reinforced thermoplastic material. The flexible fiber-reinforced thermoplastic material may have a temperature rating of at least 70° C.

An injection well system includes a well penetrating one or more subsurface formations and a tubular structure disposed in the well to provide at least a portion of a conduit in the well. The tubular structure has a tubular wall surface. The system includes a tube liner having a lay-flat state disposed inside the tubular structure. The system includes a pump in fluid communication with the tube liner. The pump is operable to inject fluid into the tube liner, where a pressure of the fluid radially expands the tube liner to conform to the tubular wall surface, thereby providing a protected portion of the conduit within the tubular structure. The tube liner may have an unstretched full diameter in a round state that is larger than an inner diameter of the tubular structure. The tube liner may be a lay-flat tubing made of a film material comprising a thermoplastic polymer. The film material may have a temperature rating of at least 70° C. Alternatively, the tube liner may be a lay-flat tubing made of a flexible fiber-reinforced thermoplastic material, which may have a temperature rating of at least 70° C. The tubular structure may comprise a casing.

The foregoing general description and the following detailed description are exemplary of the invention and are intended to provide an overview or framework for understanding the nature of the invention as it is claimed. The accompanying drawings are included to provide further understanding of the invention and are incorporated in and constitute a part of the specification. The drawings illustrate various embodiments of the invention and together with the description serve to explain the principles and operation of the invention.

BRIEF DESCRIPTION OF DRAWINGS

The following is a description of the figures in the accompanying drawings. In the drawings, identical reference numbers identify similar elements or acts. The sizes and relative positions of elements in the drawings are not necessarily drawn to scale. For example, the shapes of various elements and angles are not necessarily drawn to scale, and some of these elements may be arbitrarily enlarged and positioned to improve drawing legibility. Further, the particular shapes of the elements as drawn are not necessarily intended to convey any information regarding the actual shape of the particular elements and have been solely selected for ease of recognition in the drawing.

FIG. 1 is an elevation view of a tube liner in a lay-flat state.

FIG. 2 is an end view of the tube liner of FIG. 1 in a lay-flat state.

FIG. 3 is a perspective view of the tube liner of FIG. 1 in a round state.

FIG. 4 is a perspective view of a continuous lay-flat tubing on a spool.

FIG. 5 is a perspective view of the continuous lay-flat tubing of FIG. 4 folded lengthwise on a spool.

FIG. 6 is a schematic diagram of a system showing the continuous lay-flat tubing of FIG. 4 being deployed into a tubular structure in a well.

FIG. 7 is a schematic diagram showing another view of the system of FIG. 6.

FIG. 8 is a schematic diagram of a system showing the continuous lay-flat tubing of FIG. 4 being deployed into a tubular structure in a well, where the tubular structure is a casing having perforations.

FIG. 9 is a schematic diagram showing a dissolvable weight attached to a leading end of the continuous lay-flat tube of FIG. 6.

FIG. 10 is a schematic diagram showing a downhole tractor pulling a continuous lay-flat tube along a tubular structure in a deviated well.

FIG. 11 is a schematic diagram showing a cut portion of the continuous lay-flat tubing of FIGS. 6 and 7 secured to a wellhead.

FIG. 12 is a schematic diagram showing a pump arranged to pump fluid into a tube liner deployed into a tubular structure in a well.

FIG. 13 is a schematic diagram showing fluid pressure pushing a wall of the tube liner of FIG. 11 towards a wall surface of the tubular structure.

FIG. 14 is a schematic diagram showing the full length of tube liner of FIG. 12 expanded to conform to the tubular structure.

DETAILED DESCRIPTION

In the following detailed description, certain specific details are set forth in order to provide a thorough understanding of various disclosed implementations and embodiments. However, one skilled in the relevant art will recognize that implementations and embodiments may be practiced without one or more of these specific details, or with other methods, components, materials, and so forth. In other instances, well known features or processes associated with the hydrocarbon production systems have not been shown or described in detail to avoid unnecessarily obscuring descriptions of the implementations and embodiments. For the sake of continuity, and in the interest of conciseness, same or similar reference characters may be used for same or similar objects in multiple figures.

FIGS. 1 and 2 show a tube liner 100 to be used in lining at least a portion of a conduit in a well according to one illustrative implementation. The conduit may run from the bottom of the well to the surface. The conduit may be provided by one or more tubular structures in the well (“tubular well structures”). Examples of tubular well structures are tubulars, such as casings, installed in the well and an open hole section of the well. Tube liner 100 is a lay-flat tubing that can be radially expanded from a lay-flat state to a round state. Tube liner 100 can be deployed into a tubular structure in the lay-flat state and then radially expanded to conform to a wall surface of the tubular structure by fluid pressure, thereby lining the tubular structure. In the lay-flat state of tube liner 100 shown in FIGS. 1 and 2, tube liner 100 does not define a conduit. FIG. 3 shows tube liner 100 radially expanded to a round state. The radial expansion is achieved by applying fluid pressure to an inner surface 102 of a wall 104 of tube liner 100, as shown by the radial arrows in FIG. 3. In the round state, tube liner 100 defines a conduit. In the example of FIG. 3, the conduit has a circular cross-section. However, the conduit may have other shapes depending on the shape of the wall surface to which tube liner 100 is conformed by fluid pressure in the round state.

In one example, tube liner 100 is a lay-flat tubing made of a film material. Because the tube liner is made of a film material, the tube liner is not self-supporting. By not self-supporting, we mean that the tube liner is not rigid along its axial axis and is not rigid in the radial direction (i.e., a direction perpendicular to the axial axis). As a result, if the tube liner is placed on its side, the tube liner will collapse into a flattened state, which is the lay-flat state. Likewise, if the tube liner is placed on its end, the tube liner will collapse into a heap. In one example, a thickness of the film material may be in a range from 0.25 mil (0.00635 mm) to 10 mil (0.245 mm). In another example, a thickness of the film material may be in a range from 0.25 mil (0.00635 mm) to 5 mil (0.127 mm). In yet another example, a thickness of the film material may be in a range from 0.25 mil (0.00635 mm) to 2 mil (0.0508 mm). Preferably, the film material is a strong material that does not tear easily despite being very thin. Preferably, the film material is resistant, i.e., is not easily degraded, by acids and alkalis, such as could be encountered in a well environment. In one example, the film material is made of a thermoplastic polymer. Examples of suitable thermoplastic polymers for the film material include, but are not limited to, polyamides, such as nylon, and polyethylene terephthalate (PET). Preferably the film material can withstand high temperatures, such as temperatures that could be encountered downhole in a well, e.g., temperatures in a range from 70° C. to 120° C. The tube liner may be made by extrusion of molten material between a shaped ring or other suitable process known in the art for making a tubular shape from a film material.

In another example, tube liner 100 may be a lay-flat tubing made of a flexible fiber-reinforced thermoplastic material. The fiber and thermoplastic are in a single layer. Such material can be found in manufacture of lay-flat hose. One example of a lay-flat hose that may serve as lay-flat tubing is manufactured by extruding a thermoplastic material, such as thermoplastic polyether based polyurethane (TPU), through a cylindrical woven jacket made from high tenacity filament polymer reinforcement. A wall thickness of this flexible composite material may be around 4 mm, with a temperature rating of about 70° C. In one example, for downhole use, the flexible fiber-reinforced thermoplastic material of tube liner 100 may have a temperature rating of at least 70° C.

Wall 104 of tube liner 100 has a length L (in FIGS. 1 and 3) that can be selected based on the length of the tubular wall surface to be lined. For example, the length L may be selected to be sufficient to fully line the entire length of the tubular wall surface or to line just a portion of the length of the tubular wall surface that is to be protected from corrosion. For example, the length of tube liner 100 may be at least 50%, more preferably at least 75%, of the length of a tubular wall surface to be lined. In the lay-flat state of tube liner 100, an upper portion 104 a (in FIGS. 1 and 2) of wall 104 is flat and in opposing relation to and collapsed against a lower portion 104 b (in FIG. 2) of wall 104 that is also flat—the terms “upper” and “lower” are relative to the orientation of tube liner 100 in FIG. 2. In the lay-flat state, tube liner 100 has a width W (in FIGS. 1 and 2). Tube liner 100 can be radially expanded, as shown in FIG. 3, up to a full diameter d without stretching the material of the tube liner. The relationship between the unstretched full diameter d of tube liner 100 and width W of tube liner 100 is given by:

$\begin{matrix} {W = \frac{\pi a}{2}} & \left( 10 \right. \end{matrix}$

To line a tubular wall surface of a tubular well structure, tube liner 100 is deployed in a lay-flat state into the tubular well structure. Once a sufficient length of tube liner 100 has been deployed into the tubular well structure, tube liner 100 is then radially expanded by fluid pressure to conform wall 104 of tube liner 100 to the tubular wall surface of the tubular well structure. In one implementation, particularly if tube liner 100 is made of film material, the unstretched full diameter d (in FIG. 3) can be selected to be slightly larger than the inner diameter of the tubular well structure that is to be lined to avoid stretching the material of tube liner 100 under fluid pressure. If there are multiple inner diameters in the tubular well structure to be lined, the unstretched full diameter d of tube liner 100 can be selected to be slightly larger than the largest inner diameter of the tubular well structure. If the inner diameter (or largest inner diameter) of the tubular well structure that is to be lined is D, then:

$\begin{matrix} {d = {\frac{2W}{\pi} > D}} & (2) \end{matrix}$

FIG. 4 shows a continuous lay-flat tubing 106 wound on a spool or reel 108 in the lay-flat state. Tubing 106 is made of the same material as tube liner 100. Tube liner 100 can be a cut length (or at least a portion) of tubing 106. FIG. 5 shows that tubing 106 in the lay-flat state can be folded lengthwise, for example, to allow a shorter spool or reel 108′ to be used to support tubing 106.

FIGS. 6 and 7 show a well 110 traversing subsurface formations 121 below a surface 122. Well 110 penetrates an injection zone 120 below subsurface formations 121. Casings 112, 114 are installed in well 110 in a generally concentric arrangement (the number of casings shown are merely for illustrative purposes). Casings 112, 114 are examples of tubulars in a well. In FIGS. 6 and 7, well 110 includes an open hole section 110 a within injection zone 120 and below innermost casing 112. In this case, the tubular structure to be lined may be only innermost casing 112 or innermost casing 112 and a portion of open hole section 110 a. Preferably, all of open hole section 110 a is not lined in order to permit fluid communication with injection zone 120 through well 110. FIG. 8 shows an alternative example where casings 112′, 114, 116 are installed in well 110, and innermost casing 112′ extends into injection zone 120. In this case, casing 112′ may have perforations 118 for fluid communication with injection zone 120. In this case, the tubular structure to be lined may be innermost casing 112′. Preferably, the lining does not cover perforations 118 in order to permit fluid communication with injection zone 120 through well 110 after the lining operation.

Returning to FIGS. 6 and 7, spool 108 with continuous lay-flat tubing 106 is positioned at surface 122. Tubing 106 is being fed through a wellhead 124 at surface 122 into innermost casing 112, which is part of the tubular structure to be lined in this example (in the example shown in FIG. 8, tubing 106 is fed into innermost casing 112′). A guide plate 126 may be arranged on wellhead 124 to guide feeding of continuous tubing 106 into casing 112 (112′ in FIG. 8). Guide plate 126 may have a slot 128 to receive tubing 106.

In some cases, as illustrated in FIG. 9, a dissolvable weight 130 may be attached, e.g., by means of adhesive, to a leading end 132 of continuous lay-flat tubing 106, and the weight of dissolvable weight 130 may pull tubing 106 into casing 112 from spool 108. The dissolvable weight 130 may be a material that is soluble in water or brine. In one non-limiting example, dissolvable weight 130 may be a magnesium alloy that is dissolvable in brine.

If the tubular structure to be lined is in an inclined or highly deviated well, a downhole tractor may be used to pull continuous lay-flat tubing 106 into the tubular structure. For illustrative purposes, FIG. 10 shows a casing 112″ in a deviated portion of a well. The leading end 132 of tubing 106 is attached to a downhole tractor 134, which is then operated to pull tubing 106 along the casing 112″. A downhole tractor typically includes wheels to ride along the surface of the tubular and a drive section to propel the tractor. In general, any suitable downhole tractor, such as downhole tractors used to pull coiled tubing or other downhole equipment, may be used as downhole tractor 134. After downhole tractor 134 has reached the end of casing 112″, downhole tractor 134 may be operated to release leading end 132 of tubing 106. Downhole tractor 134 may be returned to the surface in a subsequent operation.

Returning to FIGS. 6 and 7, when a sufficient length of continuous lay-flat tubing 106 has been deployed into casing 112 (112′ in FIG. 8), tubing 106 can be cut at wellhead 124, leaving the desired length of tubing 106 inside casing 112 as tube liner 100. As shown in FIG. 11, the cut end 136 of the portion of tubing 106 in well 110, which is now tube liner 100, can be secured to wellhead 124 using any suitable method.

FIG. 12 shows a pump 138 arranged at surface 122 to pump fluid into tube liner 100. The fluid may be water, brine, or seawater, for example. FIG. 13 shows the fluid pressure pushing wall 104 of tube liner 100 towards the inner wall surface of casing 112 as fluid is pumped down tube liner 100. FIG. 14 shows the full length of tube liner 100 expanded to conform to the inner wall surface of casing 112, thereby lining casing 112. As long as there is fluid pressure acting on tube liner 100 from the inside of tube liner 100, tube liner 100 will conform to the inner surface of casing 112. (When fluid pressure is removed from tube liner 100, tube liner 100 may cling to casing 112. However, tube liner 100 may eventually fall away from casing 112 without the fluid pressure to conform tube liner 100 to casing 112.) In the illustrated example, tube liner 100 covers a portion of open hole section 110 a. However, in other examples, tube liner 100 may not cover any portion of open hole section 110 a.

The well lining method and system described may provide advantages. Tube liner 100 can be easily installed inside a tubular structure, such as casing 112, in a well without complicated equipment. When tube liner 100 conforms to a tubular wall surface of the tubular structure in the well, tube liner 100 protects the tubular wall surface from corrosive fluids while providing a conduit for flow of fluid between the well and the surface. This eliminates the need to install a separate tubing inside the tubular structure for passage of fluids that may be corrosive. Tube liner 100 can be made of relatively inexpensive material. Tube liner 100 can be installed in a tubular that is already in a well, which removes the complicated logistics for lining the tubular in the shop prior to installing the tubular in the well.

The system shown in FIG. 14 may be used as an injection well. An injection well is a device that places fluid deep underground into porous rock formations. The fluid may be water, brine, or water mixed with chemicals. For example, chemicals may be added to water to increase the viscosity and/or salinity of the water. In the oil and gas industry, water injection (also known as water flooding) is used to enhance oil recovery from a producing well. Water injection involves introducing water into the reservoir to encourage oil production. The injected water helps with the depleted pressure within the reservoir and also helps to move the oil in place. In one implementation, a water injection operation may involve lining a tubular structure, e.g., casing 112, in a well with tube liner 100 as described and then using the conduit provided by tube liner 100 to convey fluid to the injection zone, e.g., injection zone 120. Pump 138 may provide the fluid that is conveyed to injection zone 120.

While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having the benefit of this disclosure, will appreciate that other embodiments can be devised that do not depart from the scope of the invention as described herein. Accordingly, the scope of the invention should be limited only by the accompanying claims. 

What is claimed is:
 1. A method of performing an operation in a well having a conduit, the method comprising: deploying a tube liner having a lay-flat state into a tubular structure that is positioned in the well; and injecting fluid into the tube liner to radially expand the tube liner to conform to a tubular wall surface of the tubular structure and thereby provide a protected portion of the conduit within the tubular structure.
 2. The method of claim 1, wherein deploying the tube liner having the lay-flat state comprises selecting the tube liner having an unstretched full diameter in a round state that is larger than an inner diameter of the tubular structure.
 3. The method of claim 1, wherein injecting fluid into the tube liner to radially expand the tube liner to conform to a tubular wall surface of the tubular structure comprises transforming the tube liner from the lay-flat state to a round state.
 4. The method of claim 1, wherein deploying the tube liner having a lay-flat state into the tubular structure in the well comprises: providing a continuous lay-flat tubing on a spool; spooling out the continuous lay-flat tubing into the tubular structure; terminating the spooling out when a select length of the continuous lay-flat tubing has been deployed in the tubular structure; and securing the select length of the continuous lay-flat tubing deployed into the tubular structure at a surface above the well.
 5. The method of claim 4, wherein spooling out the continuous lay-flat tubing into the tubular structure comprises attaching a dissolvable weight to an end of the continuous lay-flat tubing that is fed into the tubular structure.
 6. The method of claim 4, wherein spooling out the continuous lay-flat tubing into the tubular comprises coupling a tractor to an end of the continuous lay-flat tubing that is fed into the tubular structure and operating the tractor to move along the tubular structure.
 7. The method of claim 1, wherein deploying the tube liner having the lay-flat state into the tubular structure comprises deploying a lay-flat tubing made of a film material.
 8. The method of claim 7, wherein the film of material comprises a thermoplastic polymer.
 9. The method of claim 8, wherein the film of material has a thickness in a range from 0.25 mil to 10 mil.
 10. The method of claim 8, wherein the film of material has a thickness in a range from 0.25 mil to 5 mil.
 11. The method of claim 1, wherein deploying the tube liner having the lay-flat state into the tubular structure comprises deploying a lay-flat tubing made of a flexible fiber-reinforced thermoplastic material.
 12. The method of claim 1, wherein the well penetrates an injection zone, and further comprising conveying fluid into the injection zone by pumping fluid through the tubular structure conduit.
 13. A system for performing an operation in a well, the system comprising: a tubular structure disposed in the well to provide at least a portion of a conduit in the well, the tubular structure having a tubular wall surface; a spool carrying a continuous lay-flat tubing disposed at a surface above the well, the spool operable to deploy at least a portion of the continuous lay-flat tubing into the tubular structure in the well; and a pump positioned to inject fluid into the at least a portion of the continuous lay-flat tubing disposed inside the tubular structure.
 14. The system of claim 13, wherein the continuous lay-flat tubing is made of a film material comprising a thermoplastic polymer, and wherein the film material has a thickness in a range from 0.25 mil to 10 mil.
 15. The system of claim 13, wherein the continuous lay-flat tubing is made of a flexible fiber-reinforced thermoplastic material.
 16. An injection well system comprising: a well penetrating one or more subsurface formations; a tubular structure disposed in the well to provide at least a portion of a conduit in the well, the tubular structure having a tubular wall surface; a tube liner having a lay-flat state disposed inside the tubular structure; and a pump in fluid communication with the tube liner, the pump operable to inject fluid into the tube liner, wherein pressure of the fluid radially expands the tube liner to conform to the tubular wall surface and thereby provide a protected portion of the conduit within the tubular structure.
 17. The injection well system of claim 16, wherein the tube liner has an unstretched full diameter in a round state that is larger than an inner diameter of the tubular structure.
 18. The injection well system of claim 16, wherein the tube liner is a lay-flat tubing made of a film material comprising a thermoplastic polymer and having a thickness in a range from 0.25 mil to 10 mil.
 19. The injection well system of claim 16, wherein the tube liner is a lay-flat tubing made of a flexible fiber-reinforced thermoplastic material.
 20. The injection well system of claim 16, wherein the tubular structure comprises a casing. 